Need an electrical solution: TV, Apple TV, M2P batteries, etc.

[7KJT7Y2I]

I want a portable drone system electrical source that I can easily take in my vehicle, and I want to find out if I can go with a car battery and AC inverter. The most robust solution would be a small portable generator, but in many (low-key) situations, it's not possible. I know that Goal Zero makes some powerful battery/charger combos (I have a small Yeti) but I want to go with something simpler and less expensive. I would hook up the battery to a trickle charger while not in use. Given the following electrical load, what are my car battery options? Any other ideas? - Ability to recharge Mavic 2 Pro batteries (link) a total of 20 full charges - Ability to recharge Mavic 2 Pro remote controller battery 10 times - Ability to recharge an iPhone 8 Plus a total of 10 full charges The following devices need to be able to run for at least 6 hours: - Small flatscreen TV - Apple TV - Standard wifi router DJI Mavic 2 Flight Battery Specifications Capacity – 3850 mAh. Voltage – 15.4V. Max Charging Voltage – 17.6V. Battery Type – LiPo 4S. Energy – 59.29 Wh. Net Weight – 10.4 ounces (297 grams). Max Charging Power – 80W. Mavic 2 Remote Controller Specifications Operating Frequency: 2.400 – 2.483 GHz; 5.725 – 5.850 GHz. Operating Temperature Range: 0℃ – 40℃. Battery: 3950 mAh. Operating Current/Voltage: 1800 mA ⎓ 3.83 V. Supported Mobile Device Size: Max length: 160 mm; max thickness: 6.5–8.5 mm. Supported USD Port Types: Lightning, Micro USB (Type-B), USB-C Thanks for your suggestions!

 

[WithTheBirds]

A car battery won’t do it. Starting batteries are good for short duration high current. Usable AH rating is low for size. They also don’t take many discharges to low state of charge to kill them.

Post the electrical specs for the TV and other devices and you should get some clues as to required battery ratings. LiFePO4 will likely be your most economical solution.

 

[7KJT7Y2I]

A car battery won’t do it. Starting batteries are good for short duration high current. Usable AH rating is low for size. They also don’t take many discharges to low state of charge to kill them.

Post the electrical specs for the TV and other devices and you should get some clues as to required battery ratings. LiFePO4 will likely be your most economical solution.

Thanks for the advice! I changed my mind. It sounds like a generator is the best solution. I’m asking for a lot by needing to recharge these things so many times, run a tv, router.... It’s just too much. Have any recommendations on getting a generator that can handle this? I assume I’d need a surge protector to plug in 4 outlets.

 

[bumper]

A generator would be my last choice, it'll work, but it's not as efficient at the relatively light loads you are talking about.
If you have room , you could use rigid solar panels, panel cost is about $100 - $120 for a 100 watt panel that will net you a bit more than 5 amps (up to about 6 amps with MPPT, see below). Two will get you over 10 amps etc. If room is scarce, you can use foldable panels, but they cost at least 50% more (I use a couple of foldable panels that I bungee on top of my plane's wings when I'm camping the backcountry in Idaho), very convenient, and quiet!

Using solar and a solar charge regulator, you can charge your vehicle battery and use that 12 volt source to either run a 12 volt charger for your drone directly, or you can use a small 12 VDC inverter to run 110 VAC chargers (though you'll lose some efficiency with the double conversion.

The logic to this approach is you won't need so much PV panel capacity as much of your power demand will be intermittent. Thus you can get your 12 DC power from your vehicle battery while the PV panel is charging your battery, providing much or even all the power from the battery. When your power demand drops, as when you are out flying, then the PV panels will continue to charge the battery/s at a higher rate.

A rough rule of thumb for mobile solar panel/battery systems, is to have 1 amp hour of battery capacity for each watt of solar panel. The most efficient solar charge controller type is the MPPT (maximum power point tracking). They are more expensive, they they utilize the power available from a PV panel more efficiently, providing more current output. The lower the battery state of charge, within reason, the more you gain with a MPPT controller.

 

[7KJT7Y2I]

Thanks! I’ve been meaning to find out what my options were for large solar setups for my overlanding trips

 

[DanMan32]

It all depends on how many items you want to run/charge at once.
An M2 battery charger takes at minimum 50watts per battery being charged. That leaves only 50w left off of that 100W solar panel. I suppose you could pull more if you have a battery (such as car battery) as a reserve but can you replace what was taken out of the reserve battery in time before having to draw from it again?

 

[WithTheBirds]

Solar panel ratings are almost useless in circumstances other than those where they are sized significantly larger than the max load requirement might be.

You need to factor in an inverter/charge controller and battery back.

Looking at your original wish list.........

Mavic 2 battery flown down to 15% SOC will require 44Wh.
Controller at 10% 14Wh.
Iphone 8+ full charge 9Wh

To get your 20,10,10 charge requirement for the above devices (allowing for conversion and charge efficiencies) you will need over 100Ah from a car battery. A car battery of this rating (over 250RC) will be over 40KG in weight and probably a lot larger than your idea of portable. 100Ah of LiFePO4 (4 100Ah cells series connected for 12.8V nom) will weight less than 9Kg and is much smaller than any Lead Acid wet or AGM solution.

 

[7KJT7Y2I]

It all depends on how many items you want to run/charge at once.
An M2 battery charger takes at minimum 50watts per battery being charged. That leaves only 50w left off of that 100W solar panel. I suppose you could pull more if you have a battery (such as car battery) as a reserve but can you replace what was taken out of the reserve battery in time before having to draw from it again?

I'm in a real bind here. I want very much to have a nice, clean, efficient, quiet solution in a solar panel solution. However, there's just nothing like a generator. It's a tough call for me. I want to charge one battery at a time, along with the router/AppleTV/TV. I don't need to charge two MP2 batts at the same time.

 

[WithTheBirds]

I'm in a real bind here. I want very much to have a nice, clean, efficient, quiet solution in a solar panel solution. However, there's just nothing like a generator. It's a tough call for me. I want to charge one battery at a time, along with the router/AppleTV/TV. I don't need to charge two MP2 batts at the same time.

I think it was wrongly assumed you might want to charge everything at once, that’s not how I read it. Assuming your only load on the 120w solar panel is to put 100Ah into a battery. Near enough to what is required to charge the devices you listed. That will be 2 and 1/2 days of good sunlight from the panel.

 

[7KJT7Y2I]

I think it was wrongly assumed you might want to charge everything at once, that’s not how I read it. Assuming your only load on the 120w solar panel is to put 100Ah into a battery. Near enough to what is required to charge the devices you listed. That will be 2 and 1/2 days of good sunlight from the panel.

That's better performance than I expected. Now that I see a generator consumes ~1gal/hr, that's crazy. Super inefficient

 

[WithTheBirds]

That's better performance than I expected. Now that I see a generator consumes ~1gal/hr, that's crazy. Super inefficient

That must be a big genset. My little Honda will give max 1KVA and uses less than 1/3 gal/hour to do it.

 

[DanMan32]

There's two things to consider:
Total watt load - using watts avoids having to convert to proper amps when shifting volts. IOW, 10A out at 12v is 120W, which would mean 1A in at 120v, also 120W, not accounting for watts consumed in conversion loss.

Total energy capacity/usage
Best to do this in WHr. This determines if load can be sustained, and if not, how long it can last.

 

[7KJT7Y2I]

There's two things to consider:
Total watt load - using watts avoids having to convert to proper amps when shifting volts. IOW, 10A out at 12v is 120W, which would mean 1A in at 120v, also 120W, not accounting for watts consumed in conversion loss.

Total energy capacity/usage
Best to do this in WHr. This determines if load can be sustained, and if not, how long it can last.

All of this will be made simpler if I nail down each item that needs power. What specific units should I note when I look up the electrical specs on them?

 

[DanMan32]

Watts would be universal across voltages.
If you can't find watts, you can multiply voltage times amps.
Note that V*A to get watts may be an approximation. Often the amp rating is peak amps and not nominal amps, particularly with AC input and switching power supplies.

 

[7KJT7Y2I]

This is mostly pertinent because you’re assuming that constant recharge from the sun, right?

if I were to go solely with a battery system, that’s when i should be more concened about capacity, Watt-Hours , correct?

 

[WithTheBirds]

Watts would be universal across voltages.
If you can't find watts, you can multiply voltage times amps.
Note that V*A to get watts may be an approximation. Often the amp rating is peak amps and not nominal amps, particularly with AC input and switching power supplies.

Your concern with respect to SMPS is likely irrelevant to the extent it might be safely ignored Almost all SMPS (either stand alone or incorporated in consumer electronics) include means of limiting inrush current. Even a simple thermistor will achieve this function with good performance and very low cost.

I will put money on it that the devices identified by the OP will specify the power consumption in watts on the close to the main power connection and/or in the owners manual. Operating voltage(s) will also be included and in many instances current requirement (A). It is uncommon to find a peak A rating separately specified.

 

[WithTheBirds]

All of this will be made simpler if I nail down each item that needs power. What specific units should I note when I look up the electrical specs on them?

Look at the manufacturer specified power consumption (will be stated in watts).

Also if the devices require mains power and you are going to use an inverter the efficiency rating of the inverter will be helpful (it will vary with duty cycle to a small degree). Good inverters can operate at or above 90% efficiency.

 

[DanMan32]

Your concern with respect to SMPS is likely irrelevant to the extent it might be safely ignored Almost all SMPS (either stand alone or incorporated in consumer electronics) include means of limiting inrush current. Even a simple thermistor will achieve this function with good performance and very low cost.

I will put money on it that the devices identified by the OP will specify the power consumption in watts on the close to the main power connection and/or in the owners manual. Operating voltage(s) will also be included and in many instances current requirement (A). It is uncommon to find a peak A rating separately specified.

Switching power supplies work by turning on/off input power. The peak may be 1A but with the switching duty cycling, average may only be 1/2 amp. Specs will specify the peak current so you don't blow anything by overloading.
If you do the input VA math compared to watt rating, you often find they are somewhat different.
In the case of AC, inductive loads will have a different VA compared to watts.

Just go by watts all the way, allowing for some loss in any voltage converters.

Watts: what's flowing through the pipe
Watt-Hr: what's in the tank to supply the flow through the pipe.

 

[WithTheBirds]

Switching power supplies work by turning on/off input power. The peak may be 1A but with the switching duty cycling, average may only be 1/2 amp. Specs will specify the peak current so you don't blow anything by overloading.
If you do the input VA math compared to watt rating, you often find they are somewhat different.
In the case of AC, inductive loads will have a different VA compared to watts.

Just go by watts all the way, allowing for some loss in any voltage converters.

Watts: what's flowing through the pipe
Watt-Hr: what's in the tank to supply the flow through the pipe.

Given your apparent interest in the subject you might benefit from a time investment in understanding the basic concepts. To take the most common example as taught in basic science- flow = Amps, Voltage = pressure.
Watts isn’t flow in a circuit- Amps is.


All loads other than pure resistive, i.e those with capacitive and/or inductive components, require power factor correction to arrive at the true power rating (watts). It isn’t ordinarily expressed as peak amps as you suggest. The common and accepted rating method is VA. The VA rating will often exceed the W rating, it is never less.

 

[7KJT7Y2I]

Solar panel ratings are almost useless in circumstances other than those where they are sized significantly larger than the max load requirement might be.

You need to factor in an inverter/charge controller and battery back.

Looking at your original wish list.........

Mavic 2 battery flown down to 15% SOC will require 44Wh.
Controller at 10% 14Wh.
Iphone 8+ full charge 9Wh

To get your 20,10,10 charge requirement for the above devices (allowing for conversion and charge efficiencies) you will need over 100Ah from a car battery. A car battery of this rating (over 250RC) will be over 40KG in weight and probably a lot larger than your idea of portable. 100Ah of LiFePO4 (4 100Ah cells series connected for 12.8V nom) will weight less than 9Kg and is much smaller than any Lead Acid wet or AGM solution.

I'm actually perfectly happy bringing multiple car batteries. One reason why I wanted that over solar (which I have separately, but enough to charge just a laptop, only 100W total panels) was so I didn't have to rely on sunlight, but also because it's a super robust option, if it's possible. The weight isn't an issue at all. I should have been more clear in the original post: For me, portable means it can fit in the back of an SUV. I want to be able to pull up move the 48" TV in a viewable position, and just share my screen the simplest way: sharing it over AirPlay from an AppleTV. Since I'll be bringing a router and Apple TV, I'm already going to build some kind of enclosure for that (probably just wood/plastics).

So given this, a car battery situation is fine. What kind of inverter do you think I'd need?